Any way to check if a bool** pointer to pointer contains a true value in C without loops?

Question

I am trying to optimise an iOS app and just wanted some advice on an issue I am having. I have a `bool**` which can hold up to 1024 * 1024 elements. Each element defaults to `false` but they can also be changed to `true` at random. I wanted to know if there is a streamlined way to check if a `true` value is contained by any of the elements, as, in a worst case scenario over a million iterations would be needed to do this check using two loops. I could be completely wrong but I had thought about casting the memory to an int, in the belief that, as a `false` value is equal to 0, if all the elements are false then the result of casting it to an int would, I had thought, be 0. This is not the case however. What I may have to go with is to keep a tally of the number of true values as they are toggled but this could turn quite messy very quickly. I hope I have made myself clear enough without code but, if you need to see any code, just ask. --Edit-- So I decided to go with mvp's answer. The…

Accepted Answer

Probably best optimization you can make is to convert your 1024x1024 array of booleans into array of bits. This approach has some benefits and drawbacks:

- `+` Bit array will consume 8 times less memory: 1024*1024/8 = 128KB.

- `+` You can quickly test many bits at once by checking 32-bit integers quickly. In other words, finding first non-zero bit can be 32-times as fast.

- `-` You need to create custom routines to read and write bits in this array. However, this is rather simple task - just a bit of bit twiddling :).

Any way to check if a bool** pointer to pointer contains a true value in C without loops?

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